Adaptive Fault-Tolerant Control for a Stratospheric Airship with Input Saturation and State Constraints

In this paper, an adaptive fault-tolerant control (AFTC) method based on the backstepping technique is proposed to address the trajectory tracking problem for a stratospheric airship with actuator faults. The state constraints and input saturation are considered as well. The time-varying multiplicative and additive actuator faults are modeled and estimated by the designed adaptive laws. A tan-type Barrier Lyapunov Function (BLF) is introduced to handle the state constraints problem. An auxiliary system combined with a command filter is introduced to deal with the input saturation problem. Stability analysis indicates that the tracking error is about to converge to a neighborhood of zero and the estimation errors of actuator faults are bounded. Meanwhile, the state constraints and the input saturation are never violated. The simulation results confirm that the airship can track the desired trajectory under the actuator faults, state constraints, and input saturation.